As is well known, lubricating oils are employed to minimize the wear between the moving parts of machinery. However, in spite of the most effective lubrication, wear does occur as evidenced by the congregation of minute metal particles, particularly iron particles, in the oil. A knowledge of the quantity of iron particles in a lubricating oil, as well as the rate of increase in the quantity, provides important information as regards a particular piece of machinery. Although the quantities may be small, e.g., on the order of 5 to 100 parts per million, experience may dictate that a certain amount indicates a failure condition or a trend toward such a condition.
In an aircraft engine, it is particularly important to be able to predict when engine wear, as evidenced by the presence of iron in particulate and soluble form in its lubricating oil, is approaching an undesirable level. At the present time, this information is obtained by removing an oil sample from the engine and sending it to a laboratory where a highly trained technician analyzes the sample for iron, using an atomic absorption spectrophotometer. This procedure is expensive and time consuming, resulting in a long delay between sample removal and the time corrective action, as dictated by the analytical results, can be taken.
It is an object of this invention, therefore, to provide an improved method for determining the quantity of iron wear metal present in lubricating oils in both particulate and dissolved forms.
Another object of the invention is to provide a method for conducting a rapid, on-the-spot, quantitative test for a major wear metal contained in lubricating oils.
A further object of the invention is to provide apparatus, which may be in the form of a kit, for carrying out the quantitative analysis of iron in lubricating oils.
A still further object of this invention is to provide articles of manufacture which incorporate components used in the practice of the analytical method of this invention.